/*
 * Copyright (c) 2011-2014 Pivotal Software, Inc.
 *
 *  Licensed under the Apache License, Version 2.0 (the "License");
 *  you may not use this file except in compliance with the License.
 *  You may obtain a copy of the License at
 *
 *         http://www.apache.org/licenses/LICENSE-2.0
 *
 *  Unless required by applicable law or agreed to in writing, software
 *  distributed under the License is distributed on an "AS IS" BASIS,
 *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *  See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.camunda.bpm.extension.reactor.projectreactor.config;

import org.camunda.bpm.extension.reactor.projectreactor.Environment;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.List;
import java.util.Properties;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * A {@link ConfigurationReader} that reads the configuration from properties files
 * and System properties.
 *
 * @author Andy Wilkinson
 */
public class PropertiesConfigurationReader implements ConfigurationReader {

  private static final Pattern REACTOR_NAME_PATTERN = Pattern.compile("reactor\\.dispatchers\\.(.+?)\\.type");

  private static final String FORMAT_DISPATCHER_BACKLOG = "reactor.dispatchers.%s.backlog";
  private static final String FORMAT_DISPATCHER_SIZE = "reactor.dispatchers.%s.size";
  private static final String FORMAT_DISPATCHER_TYPE = "reactor.dispatchers.%s.type";
  private static final String FORMAT_RESOURCE_NAME = "/META-INF/reactor/%s.properties";

  private static final String PROPERTY_PREFIX_REACTOR = "reactor.";

  private static final String PROPERTY_NAME_PROFILES_ACTIVE = "reactor.profiles.active";
  private static final String PROPERTY_NAME_PROFILES_DEFAULT = "reactor.profiles.default";
  private static final String PROPERTY_NAME_DEFAULT_DISPATCHER = "reactor.dispatchers.default";

  private final Logger logger = LoggerFactory.getLogger(getClass());

  private final String defaultProfileNameDefault;

  /**
   * Creates a new {@code PropertiesConfigurationReader} that, by default, will load its
   * configuration from {@code META-INF/reactor/default.properties}.
   */
  public PropertiesConfigurationReader() {
    this("reactor-environment");
  }

  public PropertiesConfigurationReader(String defaultProfileNameDefault) {
    this.defaultProfileNameDefault = defaultProfileNameDefault;
  }

  @Override
  public ReactorConfiguration read() {
    Properties configuration = new Properties();

    applyProfile(loadDefaultProfile(), configuration);

    for (Properties activeProfile : loadActiveProfiles()) {
      applyProfile(activeProfile, configuration);
    }

    applySystemProperties(configuration);

    String defaultDispatcherName = configuration.getProperty(PROPERTY_NAME_DEFAULT_DISPATCHER, Environment.SHARED);

    List<DispatcherConfiguration> dispatcherConfiguration = createDispatcherConfiguration(configuration);

    return new ReactorConfiguration(dispatcherConfiguration, defaultDispatcherName, configuration);
  }

  private Properties loadDefaultProfile() {
    String defaultProfileName = System.getProperty(PROPERTY_NAME_PROFILES_DEFAULT, defaultProfileNameDefault);
    Properties defaultProfile = loadProfile(defaultProfileName);
    return defaultProfile;
  }

  private List<Properties> loadActiveProfiles() {
    List<Properties> activeProfiles = new ArrayList<Properties>();
    if (null != System.getProperty(PROPERTY_NAME_PROFILES_ACTIVE)) {
      String[] profileNames = System.getProperty(PROPERTY_NAME_PROFILES_ACTIVE).split(",");
      for (String profileName : profileNames) {
        activeProfiles.add(loadProfile(profileName.trim()));
      }
    }
    return activeProfiles;
  }

  private void applyProfile(Properties profile, Properties configuration) {
    configuration.putAll(profile);
  }

  private void applySystemProperties(Properties configuration) {
    for (String prop : System.getProperties().stringPropertyNames()) {
      if (prop.startsWith(PROPERTY_PREFIX_REACTOR)) {
        configuration.put(prop, System.getProperty(prop));
      }
    }
  }

  private List<DispatcherConfiguration> createDispatcherConfiguration(Properties configuration) {
    List<String> dispatcherNames = getDispatcherNames(configuration);
    List<DispatcherConfiguration> dispatcherConfigurations = new ArrayList<DispatcherConfiguration>(dispatcherNames
      .size());
    for (String dispatcherName : dispatcherNames) {
      DispatcherType type = getType(dispatcherName, configuration);
      if (type != null) {
        dispatcherConfigurations.add(new DispatcherConfiguration(dispatcherName,
          type,
          getBacklog(dispatcherName,
            configuration),
          getSize(dispatcherName, configuration)));
      }
    }
    return dispatcherConfigurations;
  }

  private List<String> getDispatcherNames(Properties configuration) {
    List<String> dispatcherNames = new ArrayList<String>();

    for (Object propertyName : configuration.keySet()) {
      Matcher matcher = REACTOR_NAME_PATTERN.matcher((String) propertyName);
      if (matcher.matches()) {
        dispatcherNames.add(matcher.group(1));
      }
    }

    return dispatcherNames;
  }

  private DispatcherType getType(String dispatcherName, Properties configuration) {
    String type = configuration.getProperty(String.format(FORMAT_DISPATCHER_TYPE, dispatcherName));
    if ("dispatcherGroup".equals(type)) {
      return DispatcherType.DISPATCHER_GROUP;
    } else if ("mpsc".equals(type)) {
      return DispatcherType.MPSC;
    } else if ("ringBuffer".equals(type)) {
      return DispatcherType.RING_BUFFER;
    } else if ("synchronous".equals(type)) {
      return DispatcherType.SYNCHRONOUS;
    } else if ("threadPoolExecutor".equals(type)) {
      return DispatcherType.THREAD_POOL_EXECUTOR;
    } else if ("workQueue".equals(type)) {
      return DispatcherType.WORK_QUEUE;
    } else {
      logger.warn("The type '{}' of Dispatcher '{}' is not recognized", type, dispatcherName);
      return null;
    }
  }

  private Integer getBacklog(String dispatcherName, Properties configuration) {
    return getInteger(String.format(FORMAT_DISPATCHER_BACKLOG, dispatcherName), configuration);
  }

  private Integer getSize(String dispatcherName, Properties configuration) {
    return getInteger(String.format(FORMAT_DISPATCHER_SIZE, dispatcherName), configuration);
  }

  private Integer getInteger(String propertyName, Properties configuration) {
    String property = configuration.getProperty(propertyName);
    if (property != null) {
      return Integer.parseInt(property);
    } else {
      return null;
    }
  }

  protected Properties loadProfile(String name) {
    Properties properties = new Properties();

    try (InputStream inputStream = getClass().getResourceAsStream(String.format(FORMAT_RESOURCE_NAME, name))) {
      if (null != inputStream) {
        properties.load(inputStream);
      } else {
        logger.debug("No properties file found in the classpath at '{}' for profile '{}'", String.format(
          FORMAT_RESOURCE_NAME,
          name), name);
      }
    } catch (IOException e) {
      logger.error("Failed to load properties from '{}' for profile '{}'",
        String.format(FORMAT_RESOURCE_NAME, name),
        name,
        e);
    }

    return properties;
  }

}
